This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project is part of an ongoing effort to integrate our electrochemical sensor technologies with opportunitites in chemical sensing by photon imaging. To do this we have constructed a photon counting station for use as an illuminometer and collection of fluorescence signals through a pulled fiber optic. A Hamamatsu R464 photo-multiplier tube is used for photon detection. A National instruments PCI-6036E is used to count the events and control a uniblitz vs-25 shutter. The software interface has been constructed using Lab-View 7. The Uniblitz shutter drive utilizes a Microchip PIC16F628 micro-controller pulse width modulator to drive a boost converter, converting 5 volts to 70 volts with a single 22uh inductor. The Uniblitz driver circuit serves as the basis for a precision circuit for piezo tube control. The Pic16F628 also has on the chip a 16 bit counter, we plan to use this to eliminate the PCI-6036e allowing the device to operate from a single RS232 port. With this photon counting system we can explore the use of luminescent chemical sensors and weak florescent signals located in cells and in the boundary layers.